The present invention relates to mine roof support means and, more particularly, to expansion type anchors for securing roof bolts in drill holes.
It is a common practice to provide bail means for maintaining the expandable shell and tapered nut of a bolt anchor in assembled relation. For example, in U.S. Pat. No. 3,315,557 of Frederick P. Dickow the bail has its ends hooked through openings in the ends of two opposite expansion fingers of the shell. In U.S. Pat. No. 3,726,181 of Dickow and Lambert, the bail or retaining strap extends over the tapered nut and completely through the shell on both sides, its end portions being bent over to engage under the circular collar of the expansion shell. While such bail arrangements have in general been effective for the intended purpose, they involve structural modifications of the shell which could result in defects in the castings since metal is removed from certain portions of the shell to accommodate the bail or strap.
Accordingly, it is a principal object of the present invention to provide an expansion anchor having bail means securing a tapered nut to an expansion shell without removing metal from any parts of the shell to accommodate the bail or to provide means for securing it to the shell.
In a more general sense, the object of the invention is to provide a novel and improved mine roof bolt expansion anchor of the type having a one-piece, malleable expansion shell held in assembled relation with a tapered nut by means of a bail passing over the nut and secured at its opposite ends to the shell.
Other objects will in part be obvious and will in part appear hereinafter.